This invention relates to means for damping with oil bearings and more particularly to oil damping of thrust bearings.
This invention constitutes an improvement over the structure described in U.S. Pat. No. 3,756,672 granted to D. H. Hibner and Roger J. Comeau on Sept. 4, 1973 and assigned to the same assignee. The bearing and its oil damping means described in U.S. Pat. No. 3,756,672, supra, discloses an oil well disposed in an annular groove surrounding the outer race and sufficiently dimensioned to perform the damping functions. Namely, the slight radial movement on the outer race, excites the captured oil and dampens the vibratory motions associated with high speed rotation. Inasmuch as the load carried by this bearing is radial the oil damper is ideally suited since the radial motion is inherent in the design. It should be noted that oil damping can be applied to either race.
However, this oil damper does not lend itself to being used when it is desirous to dampen a thrust loaded bearing because the radial motion of either race would be opposed by the friction force between the thrust face of the race and the adjacent face of the bearing support. We found that we can obviate the problems associated with oil damping a thrust bearing by incorporating in addition to the conventional thrust bearing support, a support member that exhibits a low radial spring rate. This low radial spring rate will permit radial motion and allow the oil damper to function as it does in a conventional radial bearing oil damper by eliminating the friction force of the race and the adjacent face of the bearing support. The damper support design permits the stiffer damper support to take the full radial deflection of the rotor under severe operating conditions which may be occasioned by a loss of blade, severe flight loading conditions, large imbalance, etc.